Plants can modify xylem anatomy and hydraulic properties to adjust to water status. Elevated [CO2 ] can increase plant water potential via reduced stomatal conductance and water loss. This raises the question of whether elevated [CO2 ], which thus improves plant water status, will reduce the impacts of soil water deficit on xylem anatomy and hydraulic properties of plants. To analyse the impacts of water and [CO2 ] on maize stem xylem anatomy and hydraulic properties, we exposed potted maize plants to varying [CO2 ] levels (400, 700, 900, and 1,200 ppm) and water levels (full irrigation and deficit irrigation). Results showed that at current [CO2 ], vessel diameter, vessel roundness, stem cross-section area, specific hydraulic conductivity, and vulnerability to embolism decreased under deficit irrigation; yet, these impacts of deficit irrigation were reduced at elevated [CO2 ]. Across all treatments, midday stem water potential was tightly correlated with xylem traits and displayed similar responses. A distinct trade-off between efficiency and safety in stem xylem water transportation in response to water deficit was observed at current [CO2 ] but not observed at elevated [CO2 ]. The results of this study enhance our knowledge of plant hydraulic acclimation under future climate environments and provide insights into trade-offs in xylem structure and function.

中文翻译：

---

升高的[CO2]可减轻水分亏缺对玉米茎木质部解剖学和水力特性的影响。

植物可以修改木质部的解剖结构和水力特性，以适应水的状况。升高的[CO2]可通过减少气孔导度和水分流失来增加植物的水势。这就提出了一个问题，即升高的[CO2]从而改善植物的水分状况，是否会减少土壤水分亏缺对植物木质部解剖学和水力特性的影响。为了分析水和[CO2]对玉米茎木质部解剖学和水力特性的影响，我们将盆栽玉米植物暴露于不同的[CO2]水平（400、700、900和1,200 ppm）和水水平（完全灌溉和亏水灌溉）下）。结果表明，在目前的[CO2]条件下，亏缺灌溉可降低容器的直径，容器的圆度，茎的横截面积，比水力传导率和对栓塞的影响。然而，在[CO2]升高的情况下，亏水灌溉的这些影响会降低。在所有处理中，中午茎水势与木质部性状紧密相关，并显示出相似的响应。在当前[CO2]下观察到响应水分亏缺的茎木质部水运输效率与安全之间的明显权衡，但在升高的[CO2]下未观察到。这项研究的结果增强了我们对未来气候环境下植物水力适应的认识，并为木质部结构和功能的权衡取舍提供了见识。在当前[CO2]下观察到响应水分亏缺的茎木质部水运输效率与安全之间的明显权衡，但在升高的[CO2]下未观察到。这项研究的结果增强了我们对未来气候环境下植物水力适应的认识，并为木质部结构和功能的权衡取舍提供了见识。在当前[CO2]下观察到响应水分亏缺的茎木质部水运输效率与安全之间的明显权衡，但在升高的[CO2]下未观察到。这项研究的结果增强了我们对未来气候环境下植物水力适应的认识，并为木质部结构和功能的权衡取舍提供了见识。